Power supply systems, in particular systems which generate power at frequencies of >1 MHz and in particular less than 200 MHz and primarily in particular less than 90 MHz, are used for example for laser excitation, in plasma coating installations or for induction applications.
Power supply systems of this type include amplifiers which generate the power that is supplied to the plasma coating installations, induction applications, or laser excitation. In principle, there are two concepts for implementing power regulation of an amplifier. In amplitude regulation, the output power of the amplifier is regulated by means of the amplitude of the input signal. In linear operation, the efficiency of the amplifier is dependent on the amplitude. Alternatively, the output power of the amplifier can be regulated by regulating the supply voltage of the amplifier. In this type of regulation, the efficiency is kept relatively constant over a large dynamic range. However, the regulation speed and thus the regulation of the output power is relatively slow, in particular slower than in the regulation concept described first.
In a power supply system, abrupt changes in the required power may occur, for example, if an arc occurs in the plasma chamber and the supplied power accordingly has to be reduced abruptly. Neither the first nor the second aforementioned regulation concept is capable of meeting the requirements of rapid regulation combined with high efficiency over a large power range.